Configurable linear accelerator

ABSTRACT

Some embodiments include a system comprising: a particle power source configured to generate a particle power signal; a radio frequency (RF) power source configured to generate an RF power signal; a particle source configured to generate a particle beam in response to the particle power signal; a RF source configured to generate an RF signal in response to the RF power signal; and an accelerator structure configured to accelerate the particle beam in response to the RF signal; wherein a timing of the RF power signal is different from a timing of the particle power signal.

BACKGROUND

This disclosure relates to configurable linear accelerators, and triggerdistribution systems and frequency control systems for configurablelinear accelerators.

Linear accelerators are used in systems such as sophisticated medical,security inspection, communication, sterilization, and food irradiationsystems. The linear accelerator may be used as part of a system thatgenerates ionizing radiation including x-rays, gamma rays, or electronbeams. Some linear accelerators generate pulses of accelerated particlesby pulsing power supplied to a particle source and power to an RFsource. Some linear accelerators have fixed levels and timing for thepower supplied to a particle source and power supplied to an RF source,fixing the energy and dose rate (e.g., the timing and amplitude) for thepulses. Other linear accelerators may switch between two or morefactory-defined modes where each mode has an associated power suppliedto the particle source and power supplied to the RF source. The timingof the supplied power is the same for each mode. Moreover, the mode isswitched based on a predefined pattern, alternating between the twomodes.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A-C are block diagrams of configurable linear acceleratorsaccording to some embodiments.

FIGS. 2A-2H are timing diagrams illustrating various signals in aconfigurable linear accelerator according to some embodiments.

FIGS. 3A-3B are a block diagrams of a trigger distribution system in aconfigurable linear accelerator according to some embodiments.

FIG. 4A-4B are timing diagrams of signals in a trigger distributionsystem in a configurable linear accelerator according to someembodiments.

FIGS. 5A-5B are block diagrams of input and output circuits of a triggerdistribution system in a configurable linear accelerator according tosome embodiments.

FIG. 6A-6B are flowcharts illustrating techniques of operating aconfigurable linear accelerator according to some embodiments.

FIG. 7A-7B are flowcharts illustrating techniques of distributing atrigger in a configurable linear accelerator according to someembodiments.

FIGS. 8A and 8B are block diagrams of frequency control systems in aconfigurable linear accelerator according to some embodiments.

FIG. 9 is a flowchart illustrating techniques of adjusting a frequencyof an RF source of a configurable linear accelerator according to someembodiments.

FIG. 10 is a block diagram of a 2D x-ray imaging system according tosome embodiments.

DETAILED DESCRIPTION

Linear accelerators typically use a particle source configured togenerate a particle beam, such as an electron source. The particle beamis directed through an accelerator structure. The accelerator structureis a resonant structure that uses an input RF signal to accelerate theparticles in the particle beam. The accelerated particle beam isgenerated by pulsing the particle source to generate a pulse ofparticles directed at the accelerator structure. The RF signalaccelerates the particles to generate the accelerated particle beam. Aswill be described in further detail below, the particle source and theRF source may be independently controlled during operation. In addition,timing of the particle source and RF source, and/or frequency control ofthe RF source will be described in further detail below.

FIGS. 1A-1C are block diagrams of configurable linear acceleratorsaccording to some embodiments. Referring to FIG. 1A, a linearaccelerator system (or system or accelerator-based system) 100 aincludes a particle source 102, an accelerator structure 104, and an RFsource 108. The accelerator structure 104 and particle source 102 may bedisposed within an enclosure 101, such as a vacuum enclosure, vacuumtube, or the like.

The particle source 102 is a device or system configured to generate aparticle beam 114 in response to the particle power signal. For example,the particle source 102 may be an electron gun, an ion source, or otherdevice configured to generate a beam of charged particles. The particlesource 102 is configured to generate the particle beam 114 in responseto a particle power signal 118. In an example, the particle source 102can be a diode electron gun, which has two separate electric potentials,including a cathode and focusing electrode coupled to a first voltageand an anode coupled to a second voltage. In another example, theparticle source 102 can be a triode electron gun, which has threeseparate electric potentials, including the cathode and focusingelectrode coupled to a first voltage, the anode coupled to a secondvoltage, and control grid, typical above the surface of the cathode,coupled to a third voltage between the first voltage and the secondvoltage.

The particle power signal 118 is a signal that causes the particlesource 102 to generate the particle beam 114. For example, in someembodiments, the particle power signal 118 includes a high-voltagepulse, such as a pulse having an amplitude of 3 kilovolts (kV) to 39 kV.The high-voltage pulse may have a pulse width of about 2-5 microseconds(μs); however, in other embodiments, the pulse width may be different.

A particle power source 106 is a device or system configured to generatethe particle power signal 118. The particle power source 106 includespulse generation circuitry including circuitry to control at least oneof the amplitude, delay, and pulse width of a pulse in the particlepower signal 118. For example, the particle power source 106 may includehigh voltage power supplies, solid state or other high voltage/highcurrent switches, transformer networks, inductor-capacitor (LC) orresonant pulse shaping networks, one or more energy storage devices suchas capacitors, inductors, or the like. The particle power source 106 mayalso include control logic as will be described below.

In some embodiments, the particle power source 106 is configured tochange the generation of pulses of the particle power signal 118 suchthat a current pulse has one or more of the amplitude, delay, and pulsewidth different from those of a previous pulse. That is, the pulsecharacteristics may be varied from pulse to pulse. In some embodiments,the particle power source 106 is configured to generate pulses having adiscrete number of parameters. For example, the choice of amplitude ofthe pulse may be selectable from a finite set of two or more amplitudes.However, in other embodiments, the choice may be continuous, variable byan analog or digital setting, substantially continuous with digitalsteps that are relatively small, or the like. Although an amplitude hasbeen used as an example of a parameter that may be changed in discreteand continuous manners, in other embodiments, other parameters may bechanged in similar manners.

In some embodiments, the particle power signal 118 may not be a signalthat provides the power to generate the particle beam 114, but insteadmodulates the particle source 102. For example, the particle powersignal 118 may be a control signal, such as a grid voltage signal for atriode electron gun. In this example, the particle source 102 mayinclude a connection for a constant high-voltage source (notillustrated) configured to provide a high-voltage cathode voltage. Theparticle power signal 118 provides modulation of the particle beam 114.

The RF source 108 is a device or system configured to generate an RFsignal 120 in response to the RF power signal 122. For example, the RFsource 108 may be a magnetron, low power RF source coupled to a klystronRF amplifier, or other RF source 108 capable of generating microwave RFsignals in L, S, C, X, or other frequency bands as the RF signal 120.Microwaves are a form of electromagnetic radiation with wavelengthsranging from one meter (1 m) to one millimeter (1 mm) with frequenciesbetween 300 megahertz (MHz; 1 m) and 300 gigahertz (GHz; 1 mm), whichcan include ultra high frequency (UHF; 300 MHz to 3 GHz), super highfrequency (SHF; 3 to 30 GHz), and extremely high frequency (EHF;millimeter wave; 30 to 300 GHz). With electromagnetic energy rangingfrom approximately 1 GHz to 100 GHz in frequency, the microwave spectrumcan be further categorized in bands, such as L (1-2 GHz), S (2-4 GHz), C(4-8 GHz), X (8-12 GHz), Ku (12-18 GHz), K (18-26.5 GHz), Ka (26.5-40GHz), Q (33-50 GHz), U (40-60 GHz), V (50-75 GHz), W (75-110 GHz), F(90-140 GHz), and D (110-170 GHz). Band L is associated with UHF, bandsS through Ka are associated with SHF, and bands Q through D areassociated with EHF.

The RF power signal 122 is a signal that causes the RF source 108 togenerate the RF signal 120. In some embodiments, the RF power signal 122includes a high-voltage pulse, such as a pulse generated by a magnetronhaving an amplitude of approximately 20 kV to 45 kV, or a pulsegenerated by a klystron having an amplitude of approximately 100 kV to135 kV. The high-voltage pulse may have a pulse width of about 2-5microseconds (μs). However, in some embodiments, the pulse amplitude andwidth may be different than the above examples.

An RF power source 110 is a device or system configured to generate theRF power signal 122. The RF power source 110 includes pulse generationcircuitry including circuitry to control at least one of the amplitude,delay, and pulse width of a pulse in the RF power signal 122. Forexample, the RF power source 110 may include high voltage powersupplies, solid state or other high voltage/high current switches,transformer networks, LC pulse shaping networks, one or more energystorage devices such as capacitors, or the like. The RF power source 110may also include control logic as will be described below.

In some embodiments, the RF power source 110 is configured to change thegeneration of pulses of the RF power signal 122 such that a currentpulse has one or more of the amplitude, delay, and pulse width differentfrom those of a previous pulse. That is, the pulse characteristics maybe varied from pulse to pulse. In some embodiments, the RF power source110 is configured to generate pulses having a discrete number ofparameters. For example, the choice of amplitude of the pulse may beselectable from a finite set of two or more amplitudes. However, inother embodiments, the choice may be continuous, variable by an analogor digital setting, substantially continuous with digital steps that arerelatively small, or the like. Although an amplitude has been used as anexample of a parameter that may be changed in discrete and continuousmanners, in other embodiments, other parameters may be changed insimilar manners.

In some embodiments, one or more aspects of the particle power signal118 and the RF power signal 122 may be different. For example, in someembodiments, a timing of the RF power signal 122 is different of theparticle power signal 118. In other embodiments, a delay and/or pulsewidth may be different between the particle power signal 118 and the RFpower signal 122. In other embodiments, other aspects of the pulses maybe different between the particle power signal 118 and the RF powersignal 122. In addition, although single aspects have been described asbeing different, in some embodiments, multiple aspects of pulses may bedifferent between the particle power signal 118 and the RF power signal122.

The accelerator structure 104 is configured to accelerate the particlebeam 114 in response to the RF signal 120 to generate an acceleratedbeam 116. For example, the accelerator structure 104 may be a travelingwave (TW), standing wave (SW) structure, a hybrid TW-SW structure, oranother type of resonant structure. The accelerator structure 104 mayinclude multiple electrodes, waveguide structures, or the likeconfigured to receive the RF signal 120 and apply that signal to theparticle beam 114 to generate the accelerated beam 116.

In some embodiments, the particle beam 114 may be a pulsed electronbeam. A pulse of electrons is directed towards the accelerator structure104. The RF signal 120 may be a pulsed RF signal. As a result, anaccelerated electron beam 116 with pulses of accelerated particles maybe generated, directed at a target 117 to generate x-rays, or used forother purposes. For simplicity, the target 117 will not be illustratedin other figures; however, the accelerated particle beams describedherein may also be directed towards a target 117. Moreover, in someapplications a target 117 may not be used. For example, a sterilizationsystem may use the accelerated electron beam 116 itself instead of usingit to generate x-rays.

In linear accelerators, the character of the pulses in the acceleratedparticle beam 116 is dependent on the input particle beam 114 and the RFsignal 120. A given set of pulses of a particle power signal 118 and aRF power signal 122 with a particular timing generate correspondingpulses in the particle beam 114 and the RF signal 120 which in turngenerate a corresponding pulse in the accelerated particle beam 116having a particular energy and dose rate. Dose rate is the quantity ofradiation absorbed per unit of time. Some linear accelerators systemsuse common LC networks and transformers to generate signals similar tothe particle power signal 118 and a RF power signal 122. A singlehigh-voltage power source may charge a bank of capacitors, which arepart of an LC network, that are discharged into a transformer network togenerate both the signals. Once the bank of capacitors is charged, theoutput pulse was formed by discharging the capacitors into thetransformer network through a thyratron. Once the thyratron is switchedon, the capacitors would discharge through the thyratron untildischarged. The resulting pulse width is dependent on the capacitorcharge and transformer network and the delay is dependent on the controllogic. A thyratron is a type of gas-filled tube used as a high-powerelectrical switch and controlled rectifier. Because of the high currentor high-voltage, solid state switches have not been used.

This common source links the timing of the two signals of conventionallinear accelerators systems. If the timing of one is changed, the timingof the other changes as well. A different energy and dose may beselected by changing the charge on the capacitors and in other systems,different taps of the transformer network may allow for differentamplitudes. Regardless, the timing of the two is fixed. That is, thepulse width and the delays are the same. Even if from pulse to pulse, anamplitude of one of the signals may be changed, the timing remainsdependent. Furthermore, the energy and dose rate combinations wereconventionally set at design time, not configurable by the user in thefield, and followed a set pattern.

The particle power source 106 and the RF power source 110 are responsiveto a corresponding control signal 124 and 126, respectively. Controllogic 112 is coupled to the particle power source 106 and the RF powersource 110. The control logic 112 is configured to generate the controlsignals 124 and 126. The control logic 112 may include a general-purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a microcontroller, a programmable logic array(PLA), device such as a field programmable logic controller (PLC), aprogrammable logic gate array (FPGA), discrete circuits, a combinationof such devices, or the like. The control logic 112 may include internalportions, such as registers, cache memory, processing cores, counters,timers, comparators, adders, or the like, and may also include externalinterfaces, such as address and data bus interfaces, interruptinterfaces, or the like. Other interface devices, such as logiccircuitry, memory, communication interfaces, or the like may be part ofthe control logic 112 to connect the control logic 112 to particle powersource 106 and the RF power source 110 and other components. Theoperation of the control logic 112 will be described in further detailbelow with respect to FIGS. 2A-2H. While the control logic 112 isillustrated as separate from the particle power source 106 and the RFpower source 110, in some embodiments, the circuitry of the controllogic 112 may be distributed between a separate component, the particlepower source 106, and the RF power source 110 to perform the operationsdescribed below.

FIG. 1B is a block diagram of a configurable linear acceleratoraccording to some embodiments. The system 100 b may be similar to thesystem 100 a. However, in some embodiments, one or both of the particlepower source 106 and the RF power source 110 may receive power from amain power source 160. Here, both the particle power source 106 and theRF power source 110 receive power from the main power source 160;however, in other embodiments, the particle power source 106 and the RFpower source 110 may receive power from other sources, such as ahigh-voltage source.

Here, two different main power sources 160 a and 160 b are illustrated.In some embodiments, the power supplied to the particle power source 106and the RF power source 110 are different. For example, the main powersource 160 b may be configured to supply single-phase alternatingcurrent (AC) 230V power while the main power source 160 a may beconfigured to supply three-phase AC 400V power. In other embodiments,the magnitude of the power may be different, the main power sources 160a and 160 b may be the same power source or provide similar power, orthe like.

The particle power source 106 and the RF power source 110 are eachconfigured to generate the corresponding particle power signal 118 or RFpower signal 122 from the corresponding main power source 160 a or 160b, respectively. In particular, the particle power source 106 and the RFpower source 110 are not configured to generate pulses in thecorresponding particle power signal 118 or RF power signal 122 inresponse to a common high-voltage pulse. Instead, the pulse formingcircuitry used to generate each of the particle power signal 118 or RFpower signal 122 is instead within the corresponding particle powersource 106 or RF power source 110.

FIG. 1C is a block diagram of a configurable linear acceleratoraccording to some embodiments. The system 100 c may be similar to thesystem 100 a and 100 b. However, in some embodiments, the RF powersource 110 c includes a high-voltage source 162 a and the particle powersource 106 c includes a high-voltage source 162 b. That is, the RF powersource 110 c and the particle power source 106 c include separatehigh-voltage power sources 162 a and 162 b.

Each of the RF power source 110 c and the particle power source 106 c isconfigured to generate the associated RF power signal 122 or particlepower signal 118 from a high-voltage from the associated high-voltagesource 162 a or 162 b. The high-voltage sources 162 a and 162 b areconfigured to receive an input power 161 a and 161 b, respectively. Insome embodiments, the input powers 161 a and 161 b may be from a mainpower source such as the main power sources 160 b and 160 a of FIG. 1B.However, in other embodiments, the input power 161 a and 161 b may begenerated by a common high-voltage source. Accordingly, each of thehigh-voltage source 162 a and 162 b may be configured to generate adifferent internal high-voltage, charge internal capacitors, or the likeassociated with generating the associated RF power signal 122 orparticle power signal 118.

FIGS. 2A-2H are timing diagrams illustrating various signals in aconfigurable linear accelerator according to some embodiments. System100 a of FIG. 1A will be used as an example; however, the signals andtiming described herein may apply to other embodiments, such as thesystems 100 b and 100 c of FIGS. 1B and 1C. Referring to FIGS. 1A and2A, in some embodiments, a message 200 and a corresponding trigger 202may be received by the control logic 112 as the control signal 128. Insome embodiments, the message 200 and trigger 202 may be communicated tothe control logic 112 through a common communication interface, such asa single serial interface, a parallel interface, or the like. However,in other embodiments, the message 200 and trigger 202 may becommunicated on separate interfaces. For example, the message 200 may becommunicated through a serial or parallel interface through which datamay be communicated; however, the trigger 202 is communicated through asingle line, pin, wire, transmission line, differential pair, or thelike. Although particular examples of communication links or interfacesare described above, in other example, the communication links orinterfaces may be different.

The message 200 is a signal that includes indications of settings for anupcoming pulse. For example, the message 200 may include an indicationof one or more parameters of an amplitude and timing of the particlebeam 114, RF signal 120, particle power signal 118, RF power signal 122,or the like. The indication of the parameter may take a variety offorms, such as the absolute value of the parameter, a relative value ofthe parameter, a percentage of a predefined value of the parameter, apercentage of a maximum value for the parameters, an index into alook-up table for the parameter, or the like.

In some embodiments, configuration information may have been previouslytransmitted to the control logic 112. For example, the configurationinformation may include information associating an index to a particularvalue of a parameter. For example, an index of 0 may be associated witha voltage of 20 kV for the RF power signal 122 and an index of 1 may beassociated with a voltage of 40 kV. As a result, the message 200 maycontain merely the index to specify the particular voltage for the RFpower signal 122.

In response to receiving the message 200, the control logic 122 maycommunicate to the particle power source 106 and the RF power source 110information based on the message 200 for the upcoming pulse using thecontrol signals 124 and 126, respectively. This information may or maynot be in the same form as what was received by the control logic 112.For example, in some embodiments the control logic 112 may forward theconfiguration information for the upcoming pulse to the particle powersource 106 and the RF power source 110. In other embodiments, thecontrol logic 112 may transform the information, such as by transforminga desired energy and dose into amplitude and timing parameters for theparticle power source 106 and the RF power source 110. In someembodiments, the control logic 112 may transform the information intosource-specific information that may then be further transformed by theparticle power source 106 and the RF power source 110. For example, thecontrol logic 112 may transform the information into indexes which theparticle power source 106 and the RF power source 110 transform intoamplitude and timing information.

Trigger 202 represents a signal received by the control logic 112. Forexample, the trigger 202 may be a trigger received from a larger system,such as a cargo scanning system, that includes the system 100 a. Thetrigger 202 indicates a point in time from which the pulses of theparticle power signal 118 and RF power signal 122 will be generated.

The message 200 and the trigger 202 are offset in time with the triggeroccurring later. This offset in time may allow for the content of themessage 200 to be communicated to various portions of the system 100 aand/or allow for the various portions to prepare for an upcoming pulse.For example, one or both of the particle power source 106 and RF powersource 110 may need time to charge a bank of capacitors, configureswitches, or perform other operations to be prepared to generate thecorresponding particle power signal 118 and RF power signal 122 afterthe trigger 202 is received. In response to receiving a message 200, thecontrol logic 112 may communicate with the particle power source 106 andthe RF power source 110 to establish the parameters for an upcomingpulse, such as by communicating amplitude and timing information,communicating indexes to look-up-tables previously communicated to theparticle power source 106 and the RF power source 110, or the like. Inresponse, the particle power source 106 and the RF power source 110 mayprepare for generating the corresponding particle power signal 118 andthe RF power signal 120.

The control pulses 204 and 206 represent the control of the pulses ofthe particle power signal 118 and RF power signal 122, respectively. Thecontrol logic 112 is configured to receive the trigger 202 and, inresponse, cause the control pulses 204 and 206 to be generated. In someembodiments, the control pulses 204 and 206 may be communicated from thecontrol logic 112 to the particle power source 106 and the RF powersource 110. However, as will be described below, control of the overallsystem 100 a may be distributed across various subsystems with messageand trigger information communicated from the control logic 112 to thosesubsystems. For example, the control logic 112 may receive initialconfiguration information that is then divided and communicated to theparticle power source 106 and the RF power source 110.

Once the trigger 202 is received, the control pulses 204 and 206 aregenerated in response. In some embodiments, the control pulses 204 and206 may be generated as soon as possible in response to the trigger 202.However, in other embodiments, the control pulses 204 and 206 may begenerated after a delay. Here, the control pulses 204 and 206 aregenerated after a delay T1. The control pulses have a pulse width of T2.As illustrated, the control pulses 204 and 206 have the same delay T1and pulse width T2; however, as will be described below, the delay andpulse width may be different.

Although the trigger 202 is illustrated as a pulse, in some embodiments,the trigger information is communicated through the edge of the trigger202. Here, the edge is a rising edge, but in other embodiments, the edgemay be a falling edge. In addition, although the trigger 202 isillustrated as having a particular width, in other embodiments, thewidth may be different. For example, the trigger 202 may have a widththat is greater than a threshold. The trigger 202 may be processed tofilter out spurious triggers. The threshold width may be used as acriterion for determining whether the trigger 202 is a valid trigger.The delay T1 may allow for time to determine whether the trigger 202 isa valid trigger before triggering the control pulses 204 and 206.

Referring to FIGS. 1A and 2B, in some embodiments, multiple messages 200and triggers 202 may be received. In this example, two messages 200-1and 200-2 are received. After each message 200 is received, acorresponding trigger 202 is received. Here, trigger 202-1 triggerscontrol pulses 204-1 and 206-1 based on the message 200-1. Similarly,trigger 202-2 triggers control pulses 204-2 and 206-2 based on themessage 200-2. Here, the control pulses 204-1, 204-2, 206-1, and 206-2have the same delay T1 and the same pulse width T2. Each of the messages200-1 and 200-2 may have specified the same parameters. In otherembodiments, the message 200-1 may have specified the parameters whilethe message 200-2 indicated that the last set of parameters should beused.

The messages 200 and/or triggers 202 may be separated in time by acontrollable period. In some embodiments, the resulting control pulses206 may occur at a controllable pulse repetition frequency (PRF). Thus,a series of the control pulses 206 may be separated in time by a periodequal to the inverse of the pulse repetition frequency, i.e., 1/PRF. Fora given series of control pulses 206, the period between the pulses 206may be substantially the same. However, in other embodiments, the periodbetween the pulses 206 may be variable between groups of pulses orsingle pulses.

The message 200-2 has been illustrated as being later in time relativeto the trigger 202-1 and control pulses 204-1 and 206-1. For example, insome embodiments, the delay of the message 200-2 may be used to allowfor processing of data acquired by a system including the system 100 a.However, in other embodiments, the timing may be different. For example,the message 202-2 may be communicated during a time of the trigger 202-1and control pulses 204-1 and 206-1.

Referring to FIGS. 1A and 2C, the timing may be similar to that of FIG.2B. However, the message 200-3 indicates that while the delay may be thesame T1, the pulse width is a different time T3. For example, themessage 200-3 may have indicated a relative increase in the pulse widthT3, a different absolute pulse width T3, a different mode having thepulse width T3, or the like. Regardless, once the pulse is triggered bytrigger 202-3, the different pulse width T3 is used. Thus, the pulsewidth may be changed from pulse to pulse. Although only two pulses andthe associated triggers are illustrated, the pulse width may be changedfor each subsequent trigger and the associated pulse. Multipleconsecutive triggers and the associated pulses may have the sameparameters, some different parameters, or all different parameters.

Referring to FIGS. 1A and 2D, the timing may be similar to that of FIG.2C. However, the message 200-4 includes a different pulse delay T4 forcontrol pulse 206-4. Here, the message 200-4 included an indication ofthe different pulse delay T4. The different pulse delay T4 may have beencommunicated in the message 200-4 in a variety of ways as describedabove. Although a different delay for the control pulse 206-4 has beenused as an example, the delay may be different for the control pulse204-4 or different for both control pulses 204-4 and 206-4. That is, oneor both of the control pulses 204-4 and 206-4 may have the differentpulse delay T4. Moreover, the delay of the control pulses 204-4 and206-4 may be different from each other in addition to being differentfrom the delay T1.

In the various timing diagrams described above, examples of the pulsewidth and delay for the control pulses 204 and 206 have been used asexamples. In other embodiments, any combination of pulse width and delayfor the control pulses 204 and 206 may be used with some different andothers the same between current control pulses 204 and 206 and previouscontrol pulses 204 and 206. Furthermore, while the difference has beendescribed with respect to two consecutive pulses, the variousdifferences may be present between each and any of the pulses,regardless of whether any are identical or have similarities.

Referring to FIGS. 1A and 2E, the timing may be similar to that of FIG.2B. In some embodiments, the amplitude of the signal or signalsindicated in the message 200 may be different from pulse to pulse. Whilethe timing of FIG. 2B is used as an example, the amplitude or amplitudesthat are varied may be varied as in the other timing examples of FIGS.2C and 2D or other timing changes may be made.

The control pulses 204-1 and 204-2 are associated with power pulses118-1 and 118-2, respectively, of the particle power signal 118.Similarly, the control pulses 206-1 and 206-2 are associated with powerpulses 122-1 and 122-2, respectively, of the RF power signal 122. Thefirst message 200-1 may specify amplitudes for the power pulses 118-1and 122-1. In response to the trigger 202-1, the amplitudes are setaccordingly in power pulses 118-1 and 122-1.

The second message 200-2 specifies different amplitude for both thepower pulses 118-2 and 122-2. As a result, in response to trigger 202-2,the amplitudes are set accordingly. Although an increase in amplitude ofboth power pulses 118 and 122 has been used as an example, the amplitudeof any particular power pulse may not change, may decrease, and maychange by different magnitudes.

As described above, the timing and amplitude of power pulses 118 and 122may be different for each power pulse 118 and 122 from pulse to pulseand the power pulses 118 and 122 may be different from each other. Insome embodiments, the amplitude of one or more of the power pulses 118and 122 may be changed within a pulse. The voltage, pulse width, pulsedelay, and other characteristics of the pulses may be independent and/ordifferent. The RF signal 120 and particle beam 114 may have similarcorresponding characteristics as a result, affecting the acceleratedparticle beam 116. In addition, although two pulses have been used as anexample, in other embodiments, the sequence of pulses with differentparameters may be three or more.

Referring FIG. 2F, in some embodiments, a single message may beassociated with multiple triggers. For example, the timing in FIG. 2Emay be similar to that of FIG. 2B. However, the single message 200-1 isused to specify settings for pulses triggered in response to triggers202-1 and 202-2. In this example, the settings are the same as asubsequent trigger 202-2 may merely trigger pulses with the most recentsettings. However, in other embodiments, the settings may be differentaccording to information specified in the message. For example, themessage 200-1 may include information for two or more differentsubsequent pulses. In another example, the message 200-1 may define howthe pulses will change on subsequent triggers, such as an increasing ordecreasing amplitude or timing, a pattern for the changes, or the like.After each trigger, the particle power source 106 and the RF powersource 110 may be reconfigured to generate a different pulse to be readyfor the next trigger 202. For example, the control logic 112 may beginreconfiguring the particle power source 106 and the RF power source 110after generating the control pulses 204-1 and 206-1 to be ready for thetrigger 202-2. In some embodiments, the association of a single messagewith multiple triggers may allow for higher pulse rates as a message 200is not transmitted for every pulse.

Referring to FIG. 2G, the timing may be similar to that of FIG. 2B.However, the messages 200-1 and 200-2 that defined the associated pulseswere received before the trigger 202-1 for the first of the pulses. Thesecond pulse may be triggered in response to trigger 202-2 as defined bymessage 200-2. Accordingly, multiple pulses may be communicated to thecontrol logic 112 which then triggers associated control pulses 204 and206 in response to the corresponding trigger 202.

Regardless of how the association of a message 200 and a trigger 202 isestablished, in some embodiments, each trigger 202 results in a pulse.The message 200 information may be conveyed as described herein at arate such that the trigger 202 may generate a pulse at less than 30 toabout 1000 pulses per second or more.

Referring to FIG. 2H, the timing may be similar to that of FIG. 2A.However, initial configuration information and communication of pulseinformation is also illustrated. In some embodiments, at an earliertime, information 210 is communicated to the control logic 112. Thisinformation 210 includes the configuration information for the controllogic, the particle power source 106, the RF power source 110, or thelike.

In response to the information 210, the control logic 112 maycommunicate system-specific information to various sub-systems. Forexample, particle source information 212 may be communicated to theparticle power source 106 and RF source information 214 may becommunicated to the RF power source 110. The information 212 and 214 mayeach contain the system-specific information such as timing information,amplitude information, look-up-tables, calibration information, or thelike as described above.

While the information 210 is illustrated as a single packet ofinformation, the communication of the information 210 may be spread overtime, communicated over a series of operations, or the like. Similarly,the system-specific information 212 and 214, may be similarlycommunicated in a variety of ways. In some embodiments the information210, 212, and 214 are communicated after the system 100 a is turned on,but before any pulses have occurred. However, in other embodiments, theinformation 210, 212, and 214 may be communicated at any time such thatthe various sub-systems such as the particle power source 106 and the RFpower source 110 have the information to appropriately respond to amessage 200 and trigger 202, including being communicated immediatelybefore the message 200 and trigger 202. Moreover, while thecommunication of information 210, 212, and 214 has been illustrated asbeing in series with the message 200 and trigger 202, in someembodiments, the communication of information 210, 212, and 214 mayoccur while pulses are being generated. For example, as will bedescribed below, in some embodiments, multiple communication links mayconnect the control logic 112 to other sub-systems. The message 200,trigger 202, and information 210, 212, and 214 may be communicated overthese communication links in parallel.

Although communication of information to the particle power source 106and the RF power source 110 have been used as examples, in otherembodiments, additional information may be communicated to othersub-systems. For example, information may be communicated to a frequencycontrol system for the RF source 108, as described below. Moreover, insome embodiments, the information for the particle power source 106 andthe RF power source 110 may be communicated together. For example, thecontrol logic 112 may communicate the information for the particle powersource 106 and the RF power source 110 to a modulator sub-system thatthen communicates the specific information to the particle power source106 and the RF power source 110.

In some embodiments, by having independent particle power source 106 andRF power source 110, the timing may be changed as described above.Moreover, in some embodiments, both the timing and the amplitude may bechanged. This allows for independent control of energy and dose rate ofa resulting output pulse in the accelerated particle beam 116. Forexample, a user may set an energy of 4 MV and change the dose asdesired. The energy may be set for a series of pulses by setting theparameters of the RF power source 110, but the timing and/or amplitudeof the particle power source 110 may be varied to vary the dose or doserate. In a specific example, during a scan of a vehicle, the dose ratemay be significantly reduced when scanning a portion of a vehicleincluding the operator of the vehicle. The dose rate may be higher forpulses when scanning other portions of the vehicle including the cargo.For example, the reduced dose rate may be variable from 0.01 to 0.20rads/minute (rads/min.) at a particular pulse repetition frequency whilethe higher dose rate may be variable from 1 rad/min. to 30 rads/min. atthe same pulse repetition frequency. As a result, the vehicle operatormay not need to exit the vehicle during a scan, increasing throughput.In addition, a user may want to change the energy, such as changingbetween 4 MV, 5 MV and 6 MV, or the like. The independence of theparticle power source 106 and RF power source 110 allows this operation,including changing the energy and then varying the dose for that energy.In an example, the flexibility of changing the energy and dose rate canprovide better material discrimination (MD) from the scan.

Accordingly, a user may use the control logic 112 to setup and selectfrom a discrete number to an arbitrary number of modes with a variety ofdose and energy combinations. In some embodiments, a variety of modesmay be established, but only a subset is transmitted to the system 100 aas described above. If a different set of available modes is desired,another subset may be transmitted to the system 100 a as describedabove. The latter subset may or may not overlap with the former subset.Although a subset of modes has been used as an example, in someembodiments, configuration information for all possible modes may betransmitted to the system 100 a as described above.

The independence of the particle power source 106 and RF power source110 allows for a single design to operate similarly to multiple previousdesigns. In addition, the particular dose and energy combinations neednot be known when the system 100 a is ordered. If desired dose andenergy combinations change during the design process by a systemintegrator, a different system is not needed as long as the new dose andenergy combinations are within the configurability of the system 100 a.The user may change the operating conditions as desired.

FIGS. 3A-3B are block diagrams of a trigger distribution system in aconfigurable linear accelerator according to some embodiments. Thesystem 100 a of FIG. 1A will be used as an example; however, the triggerdistribution system 300 a may be used in other embodiments, such asthose of FIGS. 1B and 1C or the like. FIGS. 4A-4B are timing diagrams ofsignals in a trigger distribution system in a configurable linearaccelerator according to some embodiments.

Referring to FIGS. 1A, 3A, and 4A, the trigger distribution system 300 aincludes first, second, and third control logic 302, 304, and 306connected to a trigger bus 311. The control logic 302 may be a part ofthe control logic 112. The control logic 304 may be part of a particlesystem 305 including the particle source 102 and particle power source106. The control logic 306 may be part of an RF system 307 including theRF source 108 and the RF power source 110. Although the particle system305 and the RF system 307 are the only similarly situated systemsillustrated, in other embodiments, the trigger distribution system 300 amay include other systems connected to the trigger bus 311.

Each of the control logic 302, 304, and 306 may include ageneral-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a microcontroller, aprogrammable logic array (PLA), device such as a field programmablelogic controller (PLC), a programmable logic gate array (FPGA), discretecircuits, a combination of such devices, or the like. Each of thecontrol logic 302, 304, and 306 may include internal portions, such asregisters, cache memory, processing cores, counters such as counters350, 352, and 354, timers, comparators, adders, or the like, and mayalso include external interfaces, such as address and data businterfaces, interrupt interfaces, or the like. Other interface devices,such as logic circuitry, memory, communication interfaces, or the likemay be part of each of the control logic 302, 304, and 306 to connectthe control logic 302, 304, and 306 to particle power source 106, andthe RF power source 110, internal components of those sources 106 and110, and/or other components. Moreover, although the particle system 305and the RF system 307 are illustrated as having a single control logic304 and 306, respectively, in some embodiments, the systems may besubdivided into multiple systems, each with their own control logic witha connection to the trigger bus 311.

Trigger input 308 is an input to control logic 302 through which atrigger 400 may be received from a user. The trigger 400 may be receivedfrom a larger system that includes the system 300 a. For example, thetrigger 400 may be generated by a user interface system of the largersystem. Regardless of its source, as described above, the trigger 400may be received in a variety of ways through a variety of interfaces. Insome embodiments, the trigger input 308 is a single input, line, pin,differential input, or the like.

The trigger bus 311 may take a variety of forms. For example, thetrigger bus 311 may be a single electrical connection between a triggeroutput of the control logic 302 and a trigger input of the control logic304 and 306. In other embodiments, the trigger bus 311 may includemultiple lines, such as one for each downstream control logic such ascontrol logic 304 and 306.

Control logic 302 is configured to receive the trigger 400 and generateanother trigger 406 on the trigger bus 311 in response to the trigger400. The second trigger 406 has a delay relative to the trigger 400 of aconfigurable number of cycles of a counter of the control logic 302. Forexample, the control logic 302 may include an oscillator, such as acrystal oscillator circuit. That oscillator may be used to cycle acounter of the control logic 302. The control logic 302 may beconfigured to capture a state of the counter at the time the rising edgeof the trigger 400 is received. The control logic 302 may be configuredto output the trigger 406 after a configurable number of cycles of thatcounter. Here, time T5 represents that delay.

Signal 402 represents the time represented by the state of the counter350 relative to the trigger 400. Variability 408 represents theuncertainty of the value of the counter 350 due to factors such as astability of the oscillator, logic gate delays, and a period of thecounter. Trigger 406 is generated based on the count of the counter 350plus the configurable number of cycles of the counter 350. Thus, thetrigger 406 has an uncertainty based on that of the signal 402 andadditional factors such as the stability of the oscillator, logic gatedelays, and the period of the counter 350. The result is that thetrigger 406 generates a delay T5 from the trigger 400 with uncertainty410.

In addition to generating the trigger 406, the control logic 302 may beconfigured to perform an interrupt service routine in response to thetrigger 400. Times T6 and T7 represent a minimum and maximum expectedprocessing time for the interrupt service routine to finish execution.The difference between times T6 and T7 may be larger than theuncertainty 410. The time T5 is larger than the maximum expectedprocessing time for the interrupt service routine, that is, larger thantime T7. As a result, the occurrence of the trigger 406 is based on theproperties of an oscillator rather than on when a processor may endexecution of an interrupt service routine. In other words, the delay ingenerating the trigger 406 may mask larger uncertainties within thecontrol logic 302, resulting in a smaller uncertainty. In a particularexample, a desired delay may be 10 μs+/−2 μs. However, an uncertainty ofthe end of execution of an interrupt service routine may be +/−3 μs. Bymasking the uncertainty of the interrupt service routine, the higheraccuracy may be achieved.

Referring to FIGS. 1A, 3A, and 4B, the control logic 302 is connected totrigger bus 311. Two triggers 400-1 and 400-2 are illustrated. Usingtrigger 406-1 as an example, the control logic 302 is configured togenerate the corresponding trigger 406-1 on the trigger bus 311 asdescribed above. Each of the control logic 304 and 306 is configured toreceive the trigger 400-1 and generate a trigger 410-1 or 412-1,respectively in response. Each of these triggers 410-1 and 412-1 may begenerated in a manner similar to that of the trigger 406. That is, acounter 352 and 354 of the associated control logic 304 and 306 is usedin the generation of the triggers 410-1 and 412-1.

The triggers 410-1 and 412-1 represent signals on control interfaces 310and 312 of the control logic 304 and 306, respectively. Triggers 410-1and 412-1 and control interfaces 310 and 312 are merely examples.Although only one control interface is illustrated for each of thecontrol logic 304 and 306, in other embodiments, one or both may havemore than one control interface 310 or 312 and be configured tocommunicate more than one corresponding trigger 410-1 or 412-1. Althoughthe signals 410 and 412 are referred to as triggers, the signals may becontrol pulses as described above.

As described above, the particle system 305 may include the particlepower source 106 and particle source 102. In response to the trigger410-1, the particle power source 106 is configured to generate aparticle power signal 118. The particle source 102 is configured togenerate the particle beam 114 in response to the particle power signal118. Similarly, the RF system 307 may include the RF power source 110and the RF source 108. In response to the trigger 412-1, the RF powersource 110 is configured to generate a RF power signal 122. The RFsource 108 is configured to generate the RF signal 120 in response tothe RF power signal 122. Accordingly, the particle beam 114 and the RFsignal 120 to generate the accelerated particle beam 116 may betriggered in response to a common trigger 400-1 that resulted in othertriggers being distributed through the system 300 a to synchronize thetiming.

The operation in response to trigger 400-2 may be similar to thatdescribed with respect to trigger 400-1. However, as described above,parameters for the pulse may have changed. Accordingly, the timing ofthe triggers 410-2 and 412-2 may be different than triggers 410-1 and412-1 and the operation of the system may be different.

Referring to FIGS. 1A, 3B, 4A, and 4B, the trigger distribution system300 b may include additional communication links between the controllogic 302, 304, and 306. Here, two communication links 360 and 362 areillustrated; however, in other embodiments, only one or more than twocommunication links may be used. The communication links 360 and 362 mayinclude any communication link that allows the control logic 302, 304,and 306 to communicate information. For example, the communication links360 and 362 may include serial communication links, parallelcommunication links, a controller-area-network (CAN) bus, aninter-integrated circuit (I2C) bus, Modbus, Ethernet, or the like.

The control logic 304 and 306 may include memory 356 and 357 forconfiguration information 358 and 359. In some embodiments, theconfiguration information 358 and 359 may be communicated throughcommunication link 360. For example, the configuration information 358may include a look-up-table (LUT) including an association of an index,pulse width, pulse delay, and amplitude for a pulse of the particlesystem 305. The configuration information 358 may include multiplesimilar entries to define multiple different potential pulses of theparticle system 305. Similarly, the configuration information 359 mayinclude a look-up-table (LUT) including an association of an index,pulse width, pulse delay, and amplitude for a pulse of the RF system307. The configuration information 359 may include multiple similarentries to define multiple different potential pulses of the RF system307.

Although storing configuration information 358 and 359 has beendescribed as using a LUT, in other embodiments, other techniques may beused. For example, the configuration information 358 and 359 may includeparameters for equations defining pulse width, pulse delay, andamplitude for a pulse of the corresponding system.

In some embodiments, different types of information may be communicatedon the different communication links 360 and 362. In some embodiments,communication link 360 may be a higher-speed communication link whilecommunication link 362 may be a slower-speed communication link. Timesensitive information may be sent on the higher-speed communication link360 while configuration information is sent over the slower-speedcommunication link 362. For example, the configuration information 358and 359 may be communicated to the particle system 305 and the RF system307, respectively, over the slower communication link 362. However,information regarding an upcoming pulse may be communicated over thehigher-speed communication link 360. In a particular example, for apulse rate of 500 pulses per second, the communication of informationregarding an upcoming pulse, the configuration of various systems suchas the particle system 305 and RF system 307, the triggering of thepulse, and the actual pulse itself must occur less than 2 milliseconds(ms). The high-speed communication link 360 must be capable in thisexample of communicating the information regarding an upcoming pulse ina fraction of that time to allow for time for the other operationsassociated with a pulse.

FIGS. 5A-5B are block diagrams of input and output circuits of a triggerdistribution system in a configurable linear accelerator according tosome embodiments. In some embodiments, the circuits may be used incontrol logic of a configurable linear accelerator such as the controllogic 112, 302, 304, 306, 812, or the like as described herein.Referring to FIG. 5A, in some embodiments, an input circuit forreceiving a trigger 508 may include an oscillator 502, a counter 504,and a register 506. The oscillator 502 is configured to generate a clocksignal 514 used to increment the counter 504. The counter 504 isconfigured to output a value 512 of the counter. The trigger 508 is usedto store the current value 512 of the counter 504 in the register 506.

In some embodiments, the trigger 508 may also cause interrupt circuitry530 to set an interrupt flag 532. As a result, a processor may processan interrupt related to the trigger 508. For example, as describedabove, an interrupt service routine may be performed to determine if thetrigger 508 is a valid trigger. In some embodiments, the interruptservice routine may check the state of the trigger 508 to determine ifthe trigger 508 has remained in a high state for a time equal to orgreater than a threshold. For example, the state of the trigger 508 maybe checked while the current value of the counter 504 is less than a sumof the threshold and the value of the counter 504 stored in the register506. If the trigger 508 is not in a high state during that time, thetrigger 508 may be disregarded as a spurious trigger, also referred toas a glitch.

Referring to FIG. 5B, in some embodiments, an output circuit includesthe oscillator 502 and the counter 504. The oscillator 502 and thecounter 504 may be the same circuits, separate but synchronizedcircuits, or a combination of similar circuits. Regardless, the counter504 continues to output an incrementing value 512. The configurationregister 518 is configured to store a value 516. The comparator 520 isconfigured to compare the configuration register value 516 and thecounter value 512 to generate a comparison result 522.

Referring to FIGS. 5A and 5B, in operation, once a trigger 508 isreceived, the register 506 may store the current counter 504 value 512.This value may then be output as the stored value 510. A delay 511 innumber of cycles of the counter 504 may be added to the stored value 510in an adder 513 to generate a value 516. The value 516 may be stored inthe configuration register 518 and compared against the current value512 of the counter 504. As a result, once the counter 504 reaches thevalue 516, i.e., the sum of the stored value 510 and the delay 511, anoutput 522 may be generated, triggering an action, such as triggering apulse of the particle power signal 118 or the RF power signal 120, ortriggering another sub-system.

In some embodiments, a gating circuit, such as AND gate 550, may be usedto gate an input trigger 508. The trigger 508 may have a pulse widthgreater than the delay time plus the maximum pulse width. Once thecounter 504 reaches the value 516, i.e., the stored value 510 plus thedelay 511, the output 522 enables gate 550, the trigger 508 is gated togenerate output 554. The output 554 may be used similar to the output522 described above. A similar circuit with another configurationregister 518 storing a sum of the initial value, the delay cycles, andpulse width cycles may be used to generate another comparison result 522that is used to deactivate the output 554.

In some embodiments, circuits such as those described herein may beimplemented with input capture and output compare circuits of amicrocontroller. In particular, as the various control logic, such asthe control logic 302, 304, and 306, are distributed across a system,the microcontroller including such circuitry may reduce or eliminate aneed for external trigger distribution circuitry. Each sub-system in thesystem may include a microcontroller with input capture and outputcompare circuits.

Although a microcontroller has been used as an example, in otherembodiments, different circuits may be used to implement the triggerdistribution. For example, a programmable logic device, such as afield-programmable gate array (FPGA), a programmable logic array (PLA)or other similar circuit, may be used to implement the triggerdistribution circuitry. In another example, an application specificintegrated circuit (ASIC) may be used to implement the triggerdistribution circuitry.

Referring back to FIGS. 1A, 3B, 4B, 5A, and 5B, times T8-T11 representvarious delays associated with configuration registers 518 describedabove. For example, a value for T8 may be stored in a configurationregister 518 or other memory of the control logic 302. Thus, the trigger406 may be generated after some number of cycles according to the valuefor T8 stored in the configuration register 518 after the rising edge ofthe trigger 400.

Values for T10 and T11 may be stored in configuration registers 518 ofthe control logic 304 for the particle system 305, such as being storedin the memory 356 as part of the configuration information 358 or inother registers of the control logic 304. Accordingly, the control pulse410 may be activated a number of cycles after the rising edge of thetrigger 406. The delay from the rising edge of the trigger 400 would beabout the sum of the values T8 and T10. Similarly, the control pulse 410may be deactivated T11 cycles after the rising edge of the trigger 406or T8+T11 cycles after the rising edge of the trigger 400. Values for T9and T11 may be similarly stored in the control logic 306 of the RFsystem 307, such as being stored in the memory 357 as part of theconfiguration information 359 or in other registers of the control logic306, and the control pulse 412 may be generated accordingly. Althoughvalue T11 has been used as an example of a common end of the controlpulses 410 and 412, in other embodiments, the values may be differentfor the control pulses 410 and 412.

The values T8-T11 are used to synchronize the control pulses 410 and412. In some embodiments, the value T8 may be communicated to thecontrol logic 304 and/or 306. The control logic 304 and/or 306 mayreceive an absolute delay or pulse width from a message 200. Using thestored value T8, the appropriate values for T9-T11 may be calculated. Inother embodiments, the difference in the start for the values T9-T11 maybe built into the configuration information communicated to the controllogic 304 and 306. Thus, the control logic 304 and 306 may be able touse the exact value that value already accommodates as the current valueof T8.

In some embodiments, the value T11 or similar values defining thedeactivation of the control pulses 410 and 412 may be omitted. Asdescribed above, the trigger 406 and control pulses 410 and 412 may begated versions of the trigger 400 and trigger 406, respectively. Thus,when the trigger 400 is deactivated, the trigger 406 is deactivated and,consequently, the control pulses 410 and 412 are deactivated.

By generating the triggers and control pulses as described herein, amore accurate timing may be generated to control the pulses resulting inthe accelerated particle beam 116. As described above, the uncertaintyin an output trigger or control pulse may be on the order of a cycle ofthe oscillator 502 plus logic gate delays, variations in such delays, orthe like. This may be much smaller than the uncertainty of asoftware-based approach using an interrupt service routine. In someembodiments, as the pulses of the particle power signal 118 and the RFpower signal 122 are not generated from a common power pulse, therelative timing of the pulses may depend on the accurate distribution ofa trigger or control pulses to the particle power source 106 and RFpower source 110.

Moreover, the trigger and control pulse generation described hereinallows for configurability of the delay and pulse width. For example,registers such as configuration register 518 may be set with appropriatevalues to set the delay and pulse width relative to an incoming usertrigger 202 described above in FIGS. 2A-2H, a trigger 406 on a triggerbus 311 as described above in FIGS. 3A-3B, or the like. Multiple suchconfiguration registers 518 allow for the delay and pulse width ofmultiple pulses for multiple sub-systems to be set independently andchanged for each pulse.

As described above, embodiments having independent control of timing ofpulses of the particle system 305 and RF system 307 no longer have asingle high-voltage pulse feeding a transformer network to generate aparticle power signal 118 and an RF power signal 122. For example, whenthe particle power source 106 and RF power source 110 each include ahigh-voltage power source 162 that is separate from the other forgeneration of the associated pulses, timing information is conveyed in adifferent manner. The trigger distribution systems 300 a, 300 b, or thelike described herein are examples of how at least part of the timinginformation may be distributed to the various systems.

Although the triggers 202, 400, or the like have been described as beinggenerated by an external source, in some embodiments, the triggers maybe generated by an internal source. For example, an operator may definea pulse repetition frequency (PRF). The control logic 112 or the likemay generate a trigger 202, 400, or the like at that frequencyinternally.

Although examples of trigger distribution system have been describedabove, in other embodiments, a configurable linear accelerator systemmay include different trigger distribution systems.

FIG. 6A is a flowchart illustrating a technique of operating aconfigurable linear accelerator according to some embodiments. In 600, apulse message is received. The pulse message may be a message similar tothe message 200 described above indicating parameters for an RF powersignal and a particle power signal. For example, the control logic 112may receive a message over a communication link with absolute orrelative values for a pulse of the RF power source 110 and the particlepower source 106.

In 602, the RF power source is configured. For example, the controllogic 112 may transmit an index, absolute value, relative value, or thelike to the RF power source 110 based on the pulse message. The RF powersource 110 may be directly configured by the control logic 112 or may beconfigured to control logic in a sub-system such as control logic 306.Regardless, the RF power source 110 may be configured such as bycharging capacitors, setting states of switches, or the like to be readyfor a control pulse.

In 604, the particle power source 106 is configured in a manner similarto the RF power source 110 using the associated control logic 112 and/or304 based on the pulse message.

In 612, the particle source is driven with the particle power signal.For example, the particle power source 106 may receive a control pulsetriggering a pulse in the particle power signal 118. This drives theparticle source 102 to generate a particle beam 114.

In 614, the RF source 108 is driven with the RF power signal 122.Similar to the particle source 102, the RF power source 110 may receivea control pulse triggering a pulse in the RF power signal 122. Althoughdriving the particle source in 612 is illustrated as occurring beforedriving the RF source in 614, the timing of 612 and 614 may occur asdescribed above, with various pulse delays and/or pulse widths.

In 616, the particle beam is accelerated using the RF power signal fromthe RF source. For example, the particle source 102 directed theparticle beam 114 into the accelerator structure 102 in response to theparticle power signal 118. The RF signal 120 is applied to theaccelerator structure 104, causing the particles of the particle beam114 to accelerate.

FIG. 6B is a flowchart illustrating a technique of operating aconfigurable linear accelerator according to some embodiments. Thetechnique of FIG. 6B may be similar to that of FIG. 6A. However, in someembodiments, in 606 a trigger is received. For example, the controllogic 112 or 302 may receive a trigger. In response in 608, the particlepower signal 118 is generated and in 610 the RF power signal 122 isgenerated. As described above, triggers may be used by various controllogic is generate control pulses used to control particle systems and RFsystems.

In some embodiments, the operations described in FIGS. 6A and 6B may berepeated. For example, a second pulse message may be received in 600.The RF power source 110 and the particle power source 106 may bereconfigured based on the second pulse message in 602 and 604. Thereconfiguration may be similar or identical to the process ofconfiguring described above. As a result, the particle source 102 and RFsource 108 may be driven with the reconfigured power signals in 612 and614 such that a pulse of the accelerated particle beam 116 is generatedin 616 based on the second pulse message. Although the term second hasbeen used to describe the subsequent message, the message may be an n-thmessage with multiple intervening messages.

In particular, in some embodiments, the timing initiated by the firstpulse message may be different from the timing of the second pulsemessage. For example, a timing of the second RF power signal isdifferent from a timing of the first RF power signal or a timing of thesecond particle power signal is different from a timing of the firstparticle power signal. In some embodiments, the timing of both isdifferent. The different timing may be established by configuring theparticle power source and/or the RF power source in 602 and 604, such asby communicating new delay and pulse width parameters or indications ofthose parameters as described above.

Similarly, when configuring the particle power source 106 and/or the RFpower source 110 in 602 and 604, the amplitude of the second RF powersignal is different from an amplitude of the first RF power signal or anamplitude of the second particle power signal is different from anamplitude of the first particle power signal. In some embodiments, theamplitudes of both are different.

FIG. 7A-7B are flowcharts illustrating techniques of distributing atrigger in a configurable linear accelerator system according to someembodiments. Referring to FIG. 7A, in 700, a first trigger is received.In some embodiments the first trigger is a trigger from a larger systemincluding the configurable linear accelerator system. For example, auser interface system may generate a trigger that is received by controllogic 112, 302, or the like.

In response to the first trigger, a second trigger is generated in 708having a delay relative to the first trigger of a configurable number ofcycles of a first counter. Accordingly, the delay of the second triggeris based on the cycles of the first counter. The second trigger may be atrigger generated by the control logic 112, 302, or the like and thecounter may be part of that control logic. The second trigger may begenerated using the circuits described above, have a delay from thefirst trigger, be a gated version of the first trigger or the like asdescribed above. The second trigger may be distributed to varioussub-systems through a trigger bus.

In 710, a third trigger is generated in response to the second trigger.The third trigger has a delay relative to the second trigger of aconfigurable number of cycles of a second counter. Accordingly, thedelay of the third trigger is based on the cycles of the second counter.The third trigger may be a trigger generated by the control logic 304 orthe like and the counter may be part of that control logic. The thirdtrigger may be generated using the circuits described above, have adelay from the second trigger, be a gated version of the second triggeror the like as described above.

In 712, the particle power signal is generated in response to the thirdtrigger. As described above, the particle power source 106 may beconfigured to generate a particle power pulse having a particular delay,pulse width, and amplitude.

In 714, the particle beam is generated in response to the particle powersignal. As described above, the particle power pulse may be generatedand supplied to the particle source to generate a pulse in the particlebeam.

In some embodiments, the third trigger may be used to generate a controlpulse. In generating the control pulse, the third trigger may be used asthe control pulse or used to establish a delay. The control pulse may bea pulse with the appropriate delay and pulse width relative to the firsttrigger. In some embodiments, a second configurable number of cycles ofthe second counter is used to generate the control pulse. The secondconfigurable number of cycles of the second counter may define the pulsewidth. Thus, both the delay and the pulse width may be defined by thecycles of a counter.

In 716, a fourth trigger is generated in response to the second trigger.The fourth trigger has a delay relative to the second trigger of aconfigurable number of cycles of a third counter. Accordingly, the delayof the fourth trigger is based on the cycles of the third counter. Thefourth trigger may be a trigger generated by the control logic 306 orthe like and the counter may be part of that control logic. The fourthtrigger may be generated using the circuits described above, have adelay from the second trigger, be a gated version of the second triggeror the like as described above.

In 718, the RF power signal 122 is generated in response to the fourthtrigger. As described above, the RF power source 106 may be configuredto generate an RF signal pulse having a particular delay, pulse width,and amplitude.

In 720, the RF signal 120 is generated in response to the RF powersignal 122. As described above, the RF power signal 120 pulse may begenerated and supplied to the RF source 108 to generate a pulse in theRF signal 120.

In 722, the particle beam 114 is accelerated in response to the RFsignal 120.

In some embodiments, the fourth trigger may be used to generate acontrol pulse. In generating the control pulse, the fourth trigger maybe used as the control pulse or used to establish a delay. The controlpulse may be a pulse with the appropriate delay and pulse width relativeto the first trigger. In some embodiments, a second configurable numberof cycles of the third counter is used to generate the control pulse.The second configurable number of cycles of the third counter may definethe pulse width. Thus, both the delay and the pulse width may be definedby the cycles of a counter.

The operations in 710 and 716 are illustrated in parallel as thegeneration of the triggers and the subsequent operations in 712, 714,718, and 720 may be performed in parallel. In particular, the operationsmay be performed such that the generation of the particle beam in 714and the generation of the RF signal in 720 may be performed in parallel.The generations of the RF signal and the particle beam are generatedfrom separate third and fourth triggers. The configurable number ofcycles of the second counter and the configurable number of cycles ofthe third counter may be different. As a result, the timing of the thirdtrigger and the fourth trigger may be different.

Referring to FIG. 7B, in some embodiments the operation may be similarto that of FIG. 7A. However, in some embodiments, some operations areperformed between receiving the first trigger in 700 and generating thesecond trigger in response to the first trigger in 702. For example, in702, an interrupt service routine is performed. The interrupt serviceroutine may be performed by the control logic 112, 302, or the like.

In some embodiments, part of the interrupt service routine may be todetermine if the first trigger was a valid trigger. For example, in 704,the first trigger may be analyzed by the interrupt service routine todetermine if it is valid, such as by measuring a pulse width,determining if the first trigger has maintained an active state for athreshold period of time, or the like. If the trigger is not valid, in706, the trigger may be disregarded. The subsequent generation of thesecond trigger in 708 may not occur.

However, if the first trigger is valid in 704, the second trigger may begenerated in 708. In particular as the second trigger is generated basedon a configurable number of cycles of a counter, the delay of the secondtrigger can be isolated uncertainty in the processing of the interruptservice routine. Thus, the delay of the second trigger is greater thanand otherwise independent of the time of the end of the execution of theinterrupt service routine.

In some embodiments, the operations of FIGS. 6A and 7A or the like maybe combined. For example, the pulse message received in 600 may beassociated with the trigger received in the 700. Part of configuring theparticle power source in 604 may include determining the configurablenumber of cycles of the second counter in response to the pulse message.Part of configuring the RF power source in 602 may include determiningthe configurable number of cycles of the third counter in response tothe pulse message

FIGS. 8A and 8B are block diagrams of frequency control systems in aconfigurable linear accelerator according to some embodiments. Asdescribed above, the amplitude of the RF signal may be changed frompulse to pulse and changed in a potentially arbitrary or random pattern.In addition, with RF sources, such as a magnetron, the tuning mechanismmay not be able to be tuned on a pulse by pulse basis at pulse ratesfrom 100 to 1000 or more pulses per second. As a result, due to thechanging or potentially changing amplitude of the RF power signal asingle setpoint for a frequency control system for the RF source may beappropriate for a first sequence of amplitudes of the RF signal, may notbe appropriate for a second sequence of amplitudes of the RF signal.

Referring to FIG. 8A, the system 800 a includes a particle source 102and accelerator structure 104 similar to systems such as system 100 a,100 b, 100 c, or the like described above. The system 800 a may alsohave similar components such as the particle power source 106 and RFpower source 110, but those components are not illustrated to focus onthe frequency control system of system 800 a. The system 800 a includesan RF source 808 that may be similar to the RF source 108 describedabove. In addition, the system 800 a includes an RF system 807 includingthe RF source 808 and a RF frequency control circuit 856 including asensor 854, a feedback circuit 846, and a frequency controller 840 forthe RF source 808.

In some embodiments, the frequency controller 840 is configured toadjust a frequency of the RF source 808. For example, the RF source 808may be a magnetron and the frequency controller 840 may include a tuningmotor and a tuning slug coupled to the magnetron. In another example,the RF source 808 may be an electrically tunable source, such as a RFdriver that provides the RF signal to a klystron and the frequencycontroller 840 may include the electrical tuning circuitry for the RFdriver. However, in other embodiments, the RF source 808 may have adifferent form and may have a different frequency controller 840.

The RF source is configured to generate the RF signal 120. A sensor 854is configured to sense portions of the RF signal 120 to generate afeedback signal 844. The sensor 854 may take a variety of forms. Forexample, the sensor 854 may include directional couplers, 3 decibel (dB)hybrid couplers, phase shifters, detectors, filters, or the like. Anycircuit that can provide a feedback signal 844 that is indicative of amatch between a frequency of the RF signal and the resonant frequency ofthe accelerator structure 104 may be used as the sensor 854. In someembodiments, the feedback signal 844 includes one or more signalsrepresentative of a phase shift between a forward and a reflected signalof the RF signal or signals 120 as sensed by the sensor 854. Forexample, when the output frequency of the RF source 808 is matched tothe resonant frequency of the accelerator structure 104, the phaserelationship between the forward and reflected RF signals may have aparticular value. As the RF source 808 becomes misaligned with theaccelerator structure 104, the phase relationship changes. Feedbacksignal 844 may represent this phase shift and may be used to realign theRF signal 120.

A feedback circuit 846 is configured to receive the feedback signal 844and a setpoint signal 850. The feedback circuit 846 includes any circuitthat can combine the feedback signal 844 and the setpoint signal 850into an error signal 848. For example, the feedback circuit 846 mayinclude a general-purpose processor, a digital signal processor (DSP),an application specific integrated circuit (ASIC), a microcontroller, afield programmable gate array (FPGA), a programmable logic array (PLA),a programmable logic device, discrete circuits, a combination of suchdevices, or the like. The feedback circuit 846 may be configured toimplement a variety of control loops, such as aproportional-integral-derivative (PID) control loop. The sensor 854,feedback circuit 846, and the frequency controller 840 form an RFfrequency control circuit 856 configured to adjust the frequency of theRF source 808. The setpoint signal 850 provides a way to adjust thesetpoint of the RF frequency control circuit 856.

The system 800 a also includes control logic 812. The control logic 812may be similar to or part of the control logic 112, 302, 304, 306, orthe like described above. However, the control logic 812 is configuredto adjust a setpoint signal 850 of the RF frequency control circuit 856.In particular, the control logic 812 is configured to receive multiplesettings for the RF source 808 over time. As described above, thesettings for the RF source 808 may be changed from pulse to pulse. Thesesettings may be received in messages 852 received by the control logic812. The control logic 812 is configured to adjust the RF signal 120 inresponse to the settings, such as by adjusting an energy of the RFsignal 120. In addition, the control logic 812 is configured to adjustthe setpoint signal 850 of the RF frequency control circuit 856 inresponse to the settings, such as by adjusting the setpoint signal 850supplied to the feedback circuit 846.

The accelerator structure 104 may include a series of resonant cavitiesthat use a standing wave of RF energy to accelerate a particle beaminjected into the cavities by a particle source. The RF signal 120produced by the RF source 808 should be at the resonant frequency of thecavities in the accelerator structure 104 for the standing wave to beset up so that the particle beam 114 can be accelerated down the seriesof cavities. The RF source 808 has the frequency controller 840, such asa mechanical tuning slug that is physically turned in and out to adjustthe output frequency of the RF signal 120. The frequency controller 840is used to tune the frequency of the RF signal 120 to match that of theaccelerator structure 104.

In some embodiments, a large amount of power is produced by the RFsource 808 and coupled into the accelerator structure 104. Theefficiency of both of those components may be relatively low, causing alarge amount of heat to be absorbed by both the RF source 808 andaccelerator structure 104. This heat causes physical dimensions of theRF source 808 and accelerator structure 104 to change size, affectingboth the output frequency of the RF signal 120 and the resonantfrequency of the accelerator structure 104. Due to this effect, the RFfrequency control circuit 856 is used to adjust the output frequency ofthe RF source 808 to make sure it is matched to the resonant frequencyof the accelerator structure 104.

If the RF source 808 was being operated at a single energy level or aknown repeating variation in energy levels, the RF frequency controlcircuit 856 may be set to a single setpoint that creates an optimummatch between the frequency of the RF signal 120 and the resonantfrequency of the accelerator structure 104 for that fixed operatingcondition. However, as described above, the energy level of the RFsignal 120 may be arbitrary. The energy may change from pulse to pulsein a manner that may be determined solely by a user's discretion and thetotal range of operation.

The control logic 812 is configured to use the settings for the RFsource 808 over time to accommodate the changes in the settings. Asdescribed above, the messages 200 may be received that indicate anenergy of the RF source 808. The indication may be communicated in avariety of ways such as by index into a table, absolute value, relativevalue, or the like. Regardless, information regarding the energy ispresent in the messages 200 received by the control logic 812.

Although the settings referred to above have been in the context of amessage 200 received by control logic similar to the control logic 112described above, the source of the settings received by the controllogic 812 may be different. For example, as described above with respectto FIGS. 3A and 3B, information from a message 200 may be distributed tothe various systems, including the RF system 307. Thus, the settings maybe such specific information that was transmitted to the RF system 307and/or another system specific to the frequency control of the RF source808.

The control logic 812 is configured to use these settings to adjust thesetpoint signal 850. A single setting is not used on a one-to-one basisto set the setpoint signal 850. Rather, multiple settings are used todetermine the setpoint signal 850. In some embodiments, the controllogic 812 is configured to maintain a history of the settings includinga number of most recent settings of the settings for the RF source 808.For example, the control logic 812 may maintain a list of the mostrecent 20 settings for the RF source 808.

In response to these settings, the control logic 812 is configured toadjust the setpoint 850 of the RF frequency control circuit 856. Thecontrol logic 812 may use a variety of techniques to adjust the setpoint850. In some embodiments, the control logic 812 is configured toimplement a majority detection algorithm. The control logic 812 mayanalyze the history of settings to determine if one particular settinghas the greatest number of settings in the history. For example, thenumber of settings for each mode of operation may be determined. Inanother example, the settings may be categorized into energy levelcategories. In particular, settings that may be identified as differentmodes may have the same energy level for the RF source 808 while havingdifferent settings for the particle source 102. These may be categorizedinto the same energy level category. Similarly, settings with the sameenergy level but different pulse widths may be categorized intodifferent energy level categories. Any categorization of the settingsinto different categories may be performed.

From the categorized settings, the control logic 812 may be configuredto select a category of the energy level categories having the greatestnumber of settings. That is, one category may have a majority or aplurality of the settings among the categories. That category may beused to determine the setpoint signal 850 for the RF frequency controlcircuit 856. In a particular example, the energy associated with theselected category may be used to determine the setpoint signal 850. Thatsetpoint signal 850 is then applied to the RF frequency control circuit856.

The control logic 812 may include calibration values for a variety ofdifferent combinations of energy levels and/or pulse widths. Thesecalibration values may represent open loop settings for the feedbacksignal 844 when the frequency of the RF signal 120 is optimized for aparticular mode including a combination of an energy level, pulse width,or the like. In some embodiments, calibration values may be generatedfor each potential mode of operation of the system 800 a, includingmodes that are different only by parameters associated with the particlesource 102. In other embodiments, calibration values may be generatedthat are specific to parameters of the RF source 808. In otherembodiments, calibration values may be generated for different energylevels without regard to other parameters such as pulse width or delay.

In a particular example, when the RF signal 120 may have two differentenergy levels, the settings in the history may be analyzed to determinewhich energy setting is present in the majority of the settings. Usingthe depth of 20 settings as an example, if 11 or more of the settingsare high energy settings, that energy level may be used to determine thesetpoint signal 850 for the RF frequency control circuit 856. In someembodiments, if the number of settings of two different energy levelsare the same, the highest energy level may be selected to determine thesetpoint signal 850. Thus, if the next setting added to the history is alow energy setting and the oldest energy level is a high energy setting,the ratio of high energy to low energy would be 10:10. As a result, thehigh energy setting would be selected. If the next setting after the10:10 ratio is another low energy setting and another high energysetting is removed, the ratio of high to low energy would be 9:11. As aresult, the low energy setting would be selected.

Although a majority or plurality voting technique has been described asa way to determine an energy level to select a setpoint signal 850, thesetpoint signal 850 may be determined in other ways. For example, theenergy levels of the settings in the history may be combined together togenerate a composite energy level. That composite energy level may beused to select the setpoint signal 850, such as by selecting an energylevel associated with a calibrated setpoint signal 850 that is closestto the composite energy level, interpolating between two calibratedsetpoint signals 850 using two energy levels closets to the compositeenergy level, or the like.

In other embodiments the energy levels may be combined with weights thatincrease versus energy level. Thus, the selected setpoint signal 850 maybe weighted towards higher energy levels that may have a greater chanceof affecting the alignment of the frequency of the RF signal 120 andresonant frequency of the accelerator structure 104.

In some embodiments, the depth of the history may be selected to be longenough to provide some filtering of the changes in energy but also shortenough to meet a desired level of responsivity. For example, with apulse repetition rate of 100 pulses per second, a history depth of 20pulses may be used. Thus, the settings in the history will be thesettings of pulses over the past 0.2 seconds. In another example, thehistory may be set to have a length that is sufficient to store one ormore full cycles a repeating sequence of settings. The history may alsobe small enough so that a decision may be made with a full history in ashorter amount of time.

In some embodiments, the history may be implemented as a rolling windowof the most recent settings. For example, the history may operate as afirst-in first-out buffer with each new setting for a current orupcoming pulse being newly added to the history while the oldest settingis removed from the history.

In some embodiments, once a particular mode is selected out of theprevious history of settings, the calibration information associatedwith that mode may be used to set the setpoint 850. For example, a modeindex may be used to look up the calibration values for that mode. Thecontrol logic 812 then sets the setpoint 850 to that particularcalibrated value.

Although examples of selecting a setpoint signal 850 based on finding aclosest match to a single calibrated mode, in other embodiments,calibrations may be created for patterns of modes. For example, apredicted changing pattern of modes may be applied to the system 800 a,the frequency of the RF signal 120 may be tuned to an optimum settingwhile that pattern is being repeated. Multiple calibration values may begenerated for multiple different patterns. As will be described infurther detail below, in some embodiments, the sampling of the feedbacksignal 844 may be performed. If a pattern of modes is detected, a modehaving a higher or the highest energy may be used as the mode duringwhich the RF frequency control circuit is operated.

In some embodiments, the system 800 a includes a sample and hold (S/H)circuit 870. The S/H circuit 870 is configured to sample the feedbacksignal 844 to generate the sampled feedback signal 845 in response tocontrol signal 851. The feedback circuit 846 is configured to use thesampled feedback signal 845. As described above, the RF signal 120 maybe pulsed. The feedback signal 844 may be valid only during a pulse ofthe RF signal 120. The control logic 812 may be configured to generatethe control signal 851 to activate the S/H circuit 870 during the pulse.In some embodiments, the control logic 812 may be configured to generatethe control signal 851 with a pulse width that matches the pulse widthof the control signal 126 (illustrated in FIG. 1A). However, in otherembodiments the pulse width may be different. In some embodiments, thepulse width of the control signal 851 pulse may be fixed regardless ofmode. However, the delay of the pulse of the control signal 851 maystill be changed based on the mode.

In addition, the control logic 812 may be configured to change timing ofthe control signal 851 in response to an indication of the pulse timingfor a pulse of the RF signal 120. As described above, the delay of thepulse timing may change from pulse to pulse. The delay of the controlsignal 851 may be changed accordingly. As a result, the sampling of thefeedback signal 844 may accommodate changes in the delay of the RFsignal 120.

Moreover, as described above, the control logic 812 may select aparticular mode based on multiple settings over time to set the setpoint850. In some embodiments, the control logic 812 may select one of themodes as the mode during which the frequency control circuit 856 isactivated. The control signal 851 may be activated only during thepulses of that one of the modes. Thus, while the RF signal 120 may bepulsed, the control signal 851 may not be pulsed for each of thosepulses of the RF signal 120. As a result, the RF frequency controlcircuit 856 may be activated only for the pulses associated with aparticular mode.

Using the example of 20 settings in the history and two modes, when thehigher energy mode to lower energy mode is 11:9, the control signal 851may be activated only when the higher energy mode is pulsed. Theactivation of the control signal 851 will be activated whenever thehigher energy mode is pulsed as long as the higher energy mode is themajority in the history. However, once the ratio changes to 9:11, thecontrol signal 851 will be activated only when the lower energy mode ispulsed.

Although a S/H circuit 870 has been used as an example, in otherembodiments, the sampling may be performed in other ways. For example,the feedback signal 844 may be continuously sampled in the feedbackcircuit 846. The feedback circuit 846 may use only a portion of thedigitized feedback signal 844 corresponding to the desired pulse of theRF signal 120.

In some embodiments, the control logic 812 may be configured to store adefault setting. After a series of pulses, the state of the RF frequencycontrol circuit 856 may be in a state dependent on the last mode or thelast mode that was sampled to adjust the frequency of the RF source 808.In some embodiments, the control logic 812 may be configured to set thestate of the setpoint 850 and the state of the error signal 848 suchthat the state of the frequency control 840 of the RF source 808 is in aknown state. As a result, the repeatability of a series of pulses may beincreased. In some embodiments, after a series of pulses, the history ofsettings may be reset to all be the default setting.

Referring to FIG. 8B, the system 800 b may be similar to the system 800a described above. However, in some embodiments, a specific type ofsensor 854 or feedback path may be used. Here, forward and reversecouplers 860 are coupled between the RF source 808 and the acceleratorstructure 104. The forward and reverse couplers 860 are configured toprovide signals indicative of the supplied RF signal 120 and a signalreflected from the accelerator structure 104. The forward and reversecouplers 860 may be implemented by a four-port directional coupler,multiple couplers, or the like. Regardless, a forward and reverse signalare generated, one of which may be shifted in phase by the phase shifter862. The two resulting signals are input to a 3 dB quadrature hybridcoupler 864.

The output signals 844 a and 844 b from 3 dB hybrid coupler 864 areinput into the feedback circuit 846. The feedback circuit 846 mayinclude analog to digital converters to digitize the output signals 844a and 844 b. In some embodiments, the digitized output signals 844 a and844 b may be used as the feedback signal 844; however, in otherembodiments, the digitized output signals 844 a and 844 b may becombined, such as by being subtracted, to generate a single feedbacksignal 844. The amplitudes of these signals or the combined signalchange as the RF signal 120 drift from resonance.

Although not illustrated other components may be present in the system800 b. For example, the output signals 844 a and 844 b from 3 dB hybridcoupler 864 may be filtered to remove higher frequency components. Inaddition, various amplifiers in the feedback path may be present.

Although a specific example of a technique of generating the feedbacksignal 844 or feedback signals 844 a and 844 b have been described withrespect to FIG. 8B, in other embodiments, different techniques may beused as described with respect to FIG. 8A.

FIG. 9 is a flowchart illustrating techniques of adjusting a frequencyof an RF source of a configurable linear accelerator according to someembodiments. The system 800 a of FIG. 8A will be used as an example;however, in other embodiments, the techniques may be used in othersystems.

In 900, an RF source is operated to generate an RF signal in response toa plurality of energy level settings over time. As described above, theRF source 808 may be operated at multiple settings that may havemultiple energy levels. As a result, the RF signal 120 may have multipleenergy levels over time.

In 902, a particle beam is accelerated in response to the RF signal. Forexample, a particle beam 114 generated by the particle source 102 may beaccelerated in the accelerator structure 104 in response to an RF signal120 from an RF source 808.

In 904, a frequency of the RF source is adjusted in response to theenergy level settings. For example, the RF frequency control circuit 856may be used to control a frequency of the RF signal 120. The controllogic 812 may adjust the setpoint 850 in response to the varioussettings as described above.

As part of adjusting the frequency of the RF source, an indication of apulse timing for an upcoming RF pulse may be received. For example, asdescribed above a message 200 may be received including the indicationof the pulse timing for the RF signal 120. Accordingly, the timing ofthe RF pulse may be changed for the upcoming pulse. The timing ofsampling of feedback RF signals in the frequency control circuit 856 forthe RF source 808 is changed based on the indication of the pulsetiming.

As part of adjusting the frequency of the RF source, a history of theenergy level settings including a number of most recent energy levelsettings may be maintained. For example, as described above, the controllogic 812 may maintain a history of settings. The frequency of the RFsource may be adjusted in response to the history.

As part of adjusting the frequency of the RF source 808, the energylevel settings in the history may be categorized according to energylevel. Once categorized, a category of the energy level settings havingthe greatest number of the most recent energy level settings may beselected and the frequency of the RF source 808 may be adjusted inresponse to the selected category. For example, the control logic 812may maintain the categories, place new settings into the categories,remove old settings from the categories, or the like. From thecategories, the control logic may select one with the greatest numberand select a setpoint 850 in response.

As part of adjusting the frequency of the RF source, energy levelsettings in the history may be combined into a combined energy level.Alternatively or in addition, energy level settings in the history maybe combined into a combined energy level using weights that increaseversus energy level. The frequency of the RF source may be adjusted inresponse to the combined energy level. For example, the control logic812 may combine the energy level settings into a combined energy level.That combined energy level may be used by the control logic 812 toselect a setting for the setpoint 850.

Although operations of a configurable linear accelerator system havebeen described above in the context of particular components, in otherembodiments, the operations may be performed by different components.

FIG. 10 is a block diagram of a 2D x-ray imaging system according tosome embodiments. The imaging system 1000 includes an x-ray source 1002and a detector 1010. The x-ray source 1002 may include a configurablelinear accelerator as described above. The x-ray source 1002 is disposedrelative to the detector 1010 such that x-rays 1020 may be generated topass through a specimen 1022 and detected by the detector 1010. In aparticular example, the 2D x-ray imaging system may include a vehiclescanning system as part of a cargo scanning system.

Referring to FIGS. 1-9, some embodiments include a system, comprising: aparticle power source 106 configured to generate a particle power signal118; a radio frequency (RF) power source configured to generate an RFpower signal 120; a particle source 102 configured to generate aparticle beam 114 in response to the particle power signal 118; a RFsource 108, 808 configured to generate an RF signal in response to theRF power signal 120; and an accelerator structure 104 configured toaccelerate the particle beam 114 in response to the RF signal; wherein atiming of the RF power signal 120 is different from a timing of theparticle power signal 118.

In some embodiments, the RF power source 110 is configured to generatethe RF power signal 120 having a voltage independent of the particlepower signal 118.

In some embodiments, the RF power source 110 is configured to generatethe RF power signal 120 having a timing independent of the particlepower signal 118.

In some embodiments, a pulse width of the RF power signal 120 isdifferent from a pulse width of the particle power signal 118.

In some embodiments, a pulse delay of the RF power signal 120 isdifferent from a pulse delay of the particle power signal 118.

In some embodiments, the particle power source 106 comprises a firsthigh-voltage source 162 b configured to generate a first high-voltage inresponse to a main power source and is configured to generate theparticle power signal 118 in response to the first high-voltage; and theRF power source 110 comprises a second high-voltage source 162 aconfigured to generate a second high-voltage in response to the mainpower source and is configured to generate the RF power signal 120 inresponse to the second high-voltage.

In some embodiments, the system further comprises control logic 112,302, 304, 306, 812 coupled to the particle power source 106 and the RFpower source 110, wherein the control logic 112, 302, 304, 306, 812 isconfigured to: receive a pulse message; receive a trigger; activate theparticle power source 106 in response to the pulse message and thetrigger; and activate the RF power source 110 in response to the pulsemessage and the trigger.

In some embodiments, the system further comprises control logic 112,302, 304, 306, 812 coupled to the particle power source 106 and the RFpower source 110, wherein the control logic 112, 302, 304, 306, 812 isconfigured to: receive a plurality of pulse messages; receive aplurality of triggers, each trigger associated with a corresponding oneof the pulse messages; and for each trigger: activate the particle powersource 106 in response to the trigger and the corresponding pulsemessage; and activate the RF power source 110 in response to the triggerand the corresponding pulse message.

In some embodiments, for a first trigger and a second trigger of thetriggers: the first trigger and the second trigger are consecutive; andthe pulse message corresponding to the first trigger includes anindication of a first amplitude of one of the particle power source 106and the RF power source 110; the pulse message corresponding to thesecond trigger includes an indication of a second amplitude of the oneof the particle power source 106 and the RF power source 110; and thefirst amplitude is different from the second amplitude.

In some embodiments, for a first trigger and a second trigger of thetriggers: the first trigger and the second trigger are consecutive; andthe pulse message corresponding to the first trigger includes anindication of a first timing of one of the particle power source 106 andthe RF power source 110; the pulse message corresponding to the secondtrigger includes an indication of a second timing of the one of theparticle power source 106 and the RF power source 110; and the firsttiming is different from the second timing.

In some embodiments, for a first trigger, a second trigger, and a thirdtrigger of the triggers: the first trigger, the second trigger and thethird trigger are consecutive; and the pulse message corresponding tothe first trigger includes an indication of a first timing or amplitudeof one of the particle power source 106 and the RF power source 110; thepulse message corresponding to the second trigger includes an indicationof a second timing or amplitude of the one of the particle power source106 and the RF power source 110; the pulse message corresponding to thethird trigger includes an indication of a third timing or amplitude ofthe one of the particle power source 106 and the RF power source 110;and the first timing or amplitude is different from the third timing oramplitude.

Some embodiments include a system, comprising: a particle power source106 configured to receive a first alternating current (AC) power and afirst control signal and generate a particle power signal 118 from thefirst AC power based on the first control signal; a radio frequency (RF)power source configured to receive a second AC power a second controlsignal and generate an RF power signal 120 from the second AC powerbased on the second control signal; a particle source 102 configured togenerate a particle beam 114 in response to the particle power signal118; a RF source 108, 808 configured to generate an RF signal inresponse to the RF power signal 120; an accelerator structure 104configured to accelerate the particle beam 114 in response to the RFsignal; and control logic 112, 302, 304, 306, 812 configured to generatethe first control signal and the second control signal.

In some embodiments, for at least one set of the first control signaland the second control signal, an amplitude of the RF power signal 120is different from an amplitude of the particle power signal 118.

In some embodiments, for at least one set of the first control signaland the second control signal, a timing of the RF power signal 120 isdifferent from a timing of the particle power signal 118.

Some embodiments include a method, comprising: receiving a pulsemessage; configuring a radio frequency (RF) power source to output an RFpower signal 120 based on the pulse message; configuring a particlepower source 106 to output a particle power signal 118 based on thepulse message; driving a particle source 102 with the particle powersignal 118; driving an RF source 108, 808 with the RF power signal 120;and accelerating a particle beam 114 from the particle source 102 usingthe RF source 108, 808.

In some embodiments, the method further comprises: receiving a triggerassociated with the pulse message; generating the RF power signal 120 inresponse to the trigger; and generating the particle power signal 118 inresponse to the trigger.

In some embodiments, the RF power signal 120 is referred to as a firstRF power signal 120 and the particle power signal 118 is referred to asa first particle power signal 118, the method further comprising:receiving a second pulse message; reconfiguring the RF power source 110to output a second RF power signal 120 based on the second pulsemessage; reconfiguring the particle power source 106 to output a secondparticle power signal 118 based on the second pulse message; driving theparticle source 102 with the second particle power signal 118; anddriving the RF source 108, 808 with the second RF power signal 120;wherein the second RF power signal 120 is different from the first RFpower signal 120 or the second particle power signal 118 is differentfrom the first particle power signal 118.

In some embodiments, a timing of the second RF power signal 120 isdifferent from a timing of the first RF power signal 120 or a timing ofthe second particle power signal 118 is different from a timing of thefirst particle power signal 118.

In some embodiments, an amplitude of the second RF power signal 120 isdifferent from an amplitude of the first RF power signal 120 or anamplitude of the second particle power signal 118 is different from anamplitude of the first particle power signal 118.

In some embodiments, a timing of the RF power signal 120 is differentfrom a timing of the particle power signal 118.

Some embodiments include a system, comprising: a first control logic112, 302, 304, 306, 812 configured to receive a first trigger andgenerate a second trigger in response to the first trigger, the secondtrigger having a delay relative to the first trigger of a configurablenumber of cycles of a counter of the first control logic 112, 302, 304,306, 812; a second control logic 112, 302, 304, 306, 812 configured toreceive the second trigger and generate a third trigger in response tothe second trigger, the third trigger having a delay relative to thesecond trigger of a configurable number of cycles of a counter of thesecond control logic 112, 302, 304, 306, 812; a third control logic 112,302, 304, 306, 812 configured to receive the second trigger and generatea fourth trigger in response to the second trigger, the fourth triggerhaving a delay relative to the second trigger of a configurable numberof cycles of a counter of the third control logic 112, 302, 304, 306,812; a particle power source 106 including the second control logic 112,302, 304, 306, 812 and configured to generate a particle power signal118 in response to the third trigger; a radio frequency (RF) powersource including the third control logic 112, 302, 304, 306, 812 andconfigured to generate an RF power signal 120 in response to the fourthtrigger; a particle source 102 configured to generate a particle beam114 in response to the particle power signal 118; a RF source 108, 808configured to generate an RF signal in response to the RF power signal120; and an accelerator structure 104 configured to accelerate theparticle beam 114 in response to the RF signal.

In some embodiments, the system further comprises: a first high-voltagepower source; and a second high-voltage power source separate from thefirst high-voltage power source; wherein: the particle power source 106is configured to generate the particle power signal 118 in response tothe third trigger using the first high-voltage power source; and theradio frequency (RF) power source is configured to generate the RF powersignal 120 in response to the fourth trigger using the secondhigh-voltage power source.

In some embodiments, the configurable number of cycles of the counter ofthe second control logic 112, 302, 304, 306, 812 is different from theconfigurable number of cycles of the counter of the third control logic112, 302, 304, 306, 812.

In some embodiments, the first control logic 112, 302, 304, 306, 812 isconfigured to perform an interrupt service routine in response to thefirst trigger; and the delay relative to the first trigger isindependent of a time execution of the interrupt service routine ends.

In some embodiments, the first control logic 112, 302, 304, 306, 812 isconfigured to: receive a pulse message associated with the first triggerbefore the first trigger; transmit a first control message to the secondcontrol logic 112, 302, 304, 306, 812 indicating the configurable numberof cycles of the counter of the second control logic 112, 302, 304, 306,812; and transmit a second control message to the third control logic112, 302, 304, 306, 812 indicating the configurable number of cycles ofthe counter of the third control logic 112, 302, 304, 306, 812.

In some embodiments, the second control logic 112, 302, 304, 306, 812 isconfigured to generate a control pulse in response to the third trigger;and the particle power source 106 is configured to generate the particlepower signal 118 based on the control pulse.

In some embodiments, the second control logic 112, 302, 304, 306, 812 isconfigured to generate the control pulse based on a second configurablenumber of cycles of the counter of the second control logic 112, 302,304, 306, 812.

In some embodiments, the third control logic 112, 302, 304, 306, 812 isconfigured to generate a control pulse in response to the fourthtrigger; and the RF power source 110 is configured to generate theparticle power signal 118 based on the control pulse.

In some embodiments, the third control logic 112, 302, 304, 306, 812 isconfigured to generate the control pulse based on a second configurablenumber of cycles of the counter of the third control logic 112, 302,304, 306, 812.

Some embodiments include a method, comprising: receiving a firsttrigger; generating a second trigger in response to the first trigger,the second trigger having a delay relative to the first trigger of aconfigurable number of cycles of a first counter; generating a thirdtrigger in response to the second trigger, the third trigger having adelay relative to the second trigger of a configurable number of cyclesof a second counter; generating a fourth trigger in response to thesecond trigger, the fourth trigger having a delay relative to the secondtrigger of a configurable number of cycles of a third counter;generating a particle power signal 118 in response to the third trigger;generating a radio frequency (RF) power signal 122 in response to thefourth trigger; generating a particle beam 114 in response to theparticle power signal 118; generating an RF signal in response to the RFpower signal 120; and accelerating the particle beam 114 in response tothe RF signal.

In some embodiments, the configurable number of cycles of the secondcounter is different from the configurable number of cycles of the thirdcounter.

In some embodiments, the method further comprises: performing aninterrupt service routine in response to the first trigger; wherein thedelay relative to the first trigger is independent of a time executionof the interrupt service routine ends.

In some embodiments, receiving a pulse message associated with the firsttrigger before the first trigger; determining the configurable number ofcycles of the second counter in response to the pulse message; anddetermining the configurable number of cycles of the third counter inresponse to the pulse message.

In some embodiments, the method further comprises: generating a controlpulse in response to the third trigger; wherein generating the particlepower signal 118 comprises generating the particle power signal 118 inresponse to the control pulse.

In some embodiments, generating the control pulse comprises generatingthe control pulse based on a second configurable number of cycles of thesecond counter.

In some embodiments, generating a control pulse in response to thefourth trigger; wherein generating the RF power signal 120 comprisesgenerating the RF power signal 120 in response to the control pulse.

In some embodiments, generating the control pulse comprises generatingthe control pulse based on a second configurable number of cycles of thethird counter.

In some embodiments, generating the particle power signal 118 inresponse to the third trigger comprises generating the particle powersignal 118 using a first high-voltage 162 b power source; and generatingthe RF power signal 120 in response to the fourth trigger comprisesgenerating the RF power signal 120 using a second high-voltage powersource 162 a separate from the first high-voltage power source.

Some embodiments include a system, comprising: means for receiving afirst trigger; means for generating a second trigger in response to thefirst trigger, the second trigger having a delay relative to the firsttrigger of a configurable number of cycles of a first counter; means forgenerating a third trigger in response to the second trigger, the thirdtrigger having a delay relative to the second trigger of a configurablenumber of cycles of a second counter; means for generating a fourthtrigger in response to the second trigger, the fourth trigger having adelay relative to the second trigger of a configurable number of cyclesof a third counter; means for generating a particle power signal inresponse to the third trigger; means for generating a radio frequency(RF) power signal in response to the fourth trigger; means forgenerating a particle beam in response to the particle power signal;means for generating an RF signal in response to the RF power signal;and means for accelerating the particle beam in response to the RFsignal. Examples of the means for receiving the first trigger includethe control logic. Examples of the means for generating the secondtrigger include the control logic 112. Examples of the means forgenerating the third trigger include the control logic 304. Examples ofthe means for generating the fourth trigger include the control logic306. Examples of the means for generating a particle power signalinclude the particle power source 106. Examples of the means forgenerating an RF power signal include the RF power source 110. Examplesof the means for generating the particle beam include the particlesource 102. Examples of the means for generating the RF signal includethe RF source 108, 808. Examples of the means for accelerating theparticle beam include the accelerator structure 104.

In some embodiments, the system further comprises: means for performingan interrupt service routine in response to the first trigger; whereinthe delay relative to the first trigger is independent of a timeexecution of the interrupt service routine ends. Examples of the meansfor performing the interrupt service routine include the control logic112, 302, 304, 306.

Some embodiments include a system, comprising: an RF source 108, 808configured to generate an RF signal; an RF frequency control circuitcoupled to the RF source 108, 808 and configured to adjust a frequencyof the RF signal; an accelerator structure 104 configured to acceleratea particle beam 114 in response to the RF signal; and control logic 112,302, 304, 306, 812 configured to: receive a plurality of settings overtime for the RF source 108, 808; adjust the RF signal in response to thesettings; and adjust a setpoint of the RF frequency control circuit inresponse to the settings.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: maintain a history of settings including a number of mostrecent settings of the settings for the RF source 108, 808; and adjustthe setpoint of the RF frequency control circuit 856 in response to thehistory.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to initialize the history of settings with a default settingfor the RF source 108, 808.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: categorize the settings in the history into energy levelcategories; select a category of the energy level categories having thegreatest number of settings; and adjust the setpoint of the RF frequencycontrol circuit in response to an energy level associated with theselected category.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: combine energy levels associated with the settings in thehistory into a combined energy level; and adjust the setpoint of the RFfrequency control circuit in response to the combined energy level.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: combine energy levels associated with the settings in thehistory into a combined energy level using weights that increase versusenergy level; and adjust the setpoint of the RF frequency controlcircuit in response to the combined energy level.

In some embodiments, the history spans at time less than or equal to 0.2seconds.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: receive an indication of an energy level for an upcomingRF pulse; and add the indication of the energy level to the history.

In some embodiments, the control logic 112, 302, 304, 306, 812 isconfigured to: receive an indication of a pulse timing for an upcomingRF pulse of the RF signal 120; and change timing of sampling of one ormore feedback RF signals in a frequency control circuit 856 for the RFsource 108, 808 based on the indication of the pulse timing.

Some embodiments include a method, comprising: operating an RF source108, 808 to generate an RF signal in response to a plurality of energylevel settings over time; accelerating a particle beam 114 in responseto the RF signal; and adjusting a frequency of the RF source 108, 808 inresponse to the energy level settings.

In some embodiments, the method further comprises: receiving anindication of a pulse timing for an upcoming RF pulse; and changingtiming of sampling of feedback RF signals in a frequency control circuitfor the RF source 108, 808 based on the indication of the pulse timing.

In some embodiments, the method further comprises: maintaining a historyof the energy level settings including a number of most recent energylevel settings; and adjusting the frequency of the RF source 108, 808 inresponse to the history.

In some embodiments, the method further comprises initializing thehistory of the energy level settings with a default setting.

In some embodiments, the method further comprises: categorizing theenergy level settings in the history according to energy level;selecting a category of the energy level settings having the greatestnumber of the most recent energy level settings; and adjusting thefrequency of the RF source 108, 808 in response to the selectedcategory.

In some embodiments, the method further comprises: combining energylevel settings in the history into a combined energy level; andadjusting the frequency of the RF source 108, 808 in response to thecombined energy level.

In some embodiments, the method further comprises: combining energylevel settings in the history into a combined energy level using weightsthat increase versus energy level; and adjusting the frequency of the RFsource 108, 808 in response to the combined energy level.

In some embodiments, maintaining the history of energy level settingscomprises maintaining the history spanning a time less than or equal to0.2 seconds.

In some embodiments, the method further comprises: receiving anindication of an energy level for an upcoming RF pulse; and adding theindication of the energy level to the history.

Some embodiments include a system, comprising: means for generating anRF signal in response to a plurality of energy level settings over time;means for accelerating a particle beam in response to the RF signal; andmeans for adjusting a frequency of the RF signal in response to theenergy level settings. Examples of the means for generating an RF signalinclude the RF sources 108, 808, or the like. Examples of the means foraccelerating a particle beam include the accelerator structure 104.Examples of the means for adjusting a frequency of the RF signal includethe RF frequency control circuit 856 and control logic 812.

In some embodiments, the system further comprises: means for maintaininga history of settings including a number of most recent settings of thesettings for the RF signal; and means for adjusting a setpoint of themeans for adjusting the frequency of the RF source in response to thehistory. Examples of the means for adjusting the history of settingsinclude the control logic 818. Examples of the means for adjusting asetpoint include the control logic 818.

Although the structures, devices, methods, and systems have beendescribed in accordance with particular embodiments, one of ordinaryskill in the art will readily recognize that many variations to theparticular embodiments are possible, and any variations should thereforebe considered to be within the spirit and scope disclosed herein.Accordingly, many modifications may be made by one of ordinary skill inthe art without departing from the spirit and scope of the appendedclaims.

The claims following this written disclosure are hereby expresslyincorporated into the present written disclosure, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.Moreover, additional embodiments capable of derivation from theindependent and dependent claims that follow are also expresslyincorporated into the present written description. These additionalembodiments are determined by replacing the dependency of a givendependent claim with the phrase “any of the claims beginning with claim[x] and ending with the claim that immediately precedes this one,” wherethe bracketed term “[x]” is replaced with the number of the mostrecently recited independent claim. For example, for the first claim setthat begins with independent claim 1, claim 3 can depend from either ofclaims 1 and 2, with these separate dependencies yielding two distinctembodiments; claim 4 can depend from any one of claim 1, 2, or 3, withthese separate dependencies yielding three distinct embodiments; claim 5can depend from any one of claim 1, 2, 3, or 4, with these separatedependencies yielding four distinct embodiments; and so on.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements specifically recited inmeans-plus-function format, if any, are intended to be construed tocover the corresponding structure, material, or acts described hereinand equivalents thereof in accordance with 35 U.S.C. § 112 ¶6.Embodiments of the invention in which an exclusive property or privilegeis claimed are defined as follows.

1. A system, comprising: a particle power source configured to generatea particle power signal; a radio frequency (RF) power source configuredto generate an RF power signal; a particle source configured to generatea particle beam in response to the particle power signal; a RF sourceconfigured to generate an RF signal in response to the RF power signal;and an accelerator structure configured to accelerate the particle beamin response to the RF signal; wherein a timing of the RF power signal isdifferent from a timing of the particle power signal.
 2. The system ofclaim 1, wherein the RF power source is configured to generate the RFpower signal having a voltage independent of the particle power signal.3. The system of claim 1, wherein the RF power source is configured togenerate the RF power signal having a timing independent of the particlepower signal.
 4. The system of claim 3, wherein a pulse width of the RFpower signal is different from a pulse width of the particle powersignal.
 5. The system of claim 3, wherein a pulse delay of the RF powersignal is different from a pulse delay of the particle power signal. 6.The system of claim 1, wherein: the particle power source comprises afirst high-voltage source configured to generate a first high-voltage inresponse to a main power source and is configured to generate theparticle power signal in response to the first high-voltage; and the RFpower source comprises a second high-voltage source configured togenerate a second high-voltage in response to the main power source andis configured to generate the RF power signal in response to the secondhigh-voltage.
 7. The system of claim 1, further comprising control logiccoupled to the particle power source and the RF power source, whereinthe control logic is configured to: receive a pulse message; receive atrigger; activate the particle power source in response to the pulsemessage and the trigger; and activate the RF power source in response tothe pulse message and the trigger.
 8. The system of claim 1, furthercomprising control logic coupled to the particle power source and the RFpower source, wherein the control logic is configured to: receive aplurality of pulse messages; receive a plurality of triggers, eachtrigger associated with a corresponding one of the pulse messages; andfor each trigger: activate the particle power source in response to thetrigger and the corresponding pulse message; and activate the RF powersource in response to the trigger and the corresponding pulse message.9. The system of claim 8, wherein for a first trigger and a secondtrigger of the triggers: the first trigger and the second trigger areconsecutive; and the pulse message corresponding to the first triggerincludes an indication of a first amplitude of one of the particle powersource and the RF power source; the pulse message corresponding to thesecond trigger includes an indication of a second amplitude of the oneof the particle power source and the RF power source; and the firstamplitude is different from the second amplitude.
 10. The system ofclaim 8, wherein for a first trigger and a second trigger of thetriggers: the first trigger and the second trigger are consecutive; andthe pulse message corresponding to the first trigger includes anindication of a first timing of one of the particle power source and theRF power source; the pulse message corresponding to the second triggerincludes an indication of a second timing of the one of the particlepower source and the RF power source; and the first timing is differentfrom the second timing.
 11. The system of claim 8, wherein for a firsttrigger, a second trigger, and a third trigger of the triggers: thefirst trigger, the second trigger and the third trigger are consecutive;and the pulse message corresponding to the first trigger includes anindication of a first timing or amplitude of one of the particle powersource and the RF power source; the pulse message corresponding to thesecond trigger includes an indication of a second timing or amplitude ofthe one of the particle power source and the RF power source; the pulsemessage corresponding to the third trigger includes an indication of athird timing or amplitude of the one of the particle power source andthe RF power source; and the first timing or amplitude is different fromthe third timing or amplitude.
 12. A system, comprising: a particlepower source configured to receive a first alternating current (AC)power and a first control signal and generate a particle power signalfrom the first AC power based on the first control signal; a radiofrequency (RF) power source configured to receive a second AC power asecond control signal and generate an RF power signal from the second ACpower based on the second control signal; a particle source configuredto generate a particle beam in response to the particle power signal; aRF source configured to generate an RF signal in response to the RFpower signal; an accelerator structure configured to accelerate theparticle beam in response to the RF signal; and control logic configuredto generate the first control signal and the second control signal. 13.The system of claim 12, wherein for at least one set of the firstcontrol signal and the second control signal, an amplitude of the RFpower signal is different from an amplitude of the particle powersignal.
 14. The system of claim 12, wherein for at least one set of thefirst control signal and the second control signal, a timing of the RFpower signal is different from a timing of the particle power signal.15. A method, comprising: receiving a pulse message; configuring a radiofrequency (RF) power source to output an RF power signal based on thepulse message; configuring a particle power source to output a particlepower signal based on the pulse message; driving a particle source withthe particle power signal; driving an RF source with the RF powersignal; and accelerating a particle beam from the particle source usingthe RF source.
 16. The method of claim 15, wherein a timing of the RFpower signal is different from a timing of the particle power signal.17. The method of claim 15, further comprising: receiving a triggerassociated with the pulse message; generating the RF power signal inresponse to the trigger; and generating the particle power signal inresponse to the trigger.
 18. The method of claim 15, wherein the RFpower signal is referred to as a first RF power signal and the particlepower signal is referred to as a first particle power signal, the methodfurther comprising: receiving a second pulse message; reconfiguring theRF power source to output a second RF power signal based on the secondpulse message; reconfiguring the particle power source to output asecond particle power signal based on the second pulse message; drivingthe particle source with the second particle power signal; and drivingthe RF source with the second RF power signal; wherein the second RFpower signal is different from the first RF power signal or the secondparticle power signal is different from the first particle power signal.19. The method of claim 18, wherein a timing of the second RF powersignal is different from a timing of the first RF power signal or atiming of the second particle power signal is different from a timing ofthe first particle power signal.
 20. The method of claim 18, wherein anamplitude of the second RF power signal is different from an amplitudeof the first RF power signal or an amplitude of the second particlepower signal is different from an amplitude of the first particle powersignal.